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Mg3Sb2-based thermoelectrics show great promise for next-generation thermoelectric power generators and coolers owing to their excellent figure of merit (zT) and earth-abundant composition elements. However, the complexity of the defect microstructure hinders the advancement of high performance. Here, the defect microstructure is modified via In doping and prolonged sintering time to realize the reduced structural disorder and microstructural evolution, synergistically optimizing electron and phonon transport via a delocalization effect. As a result, an excellent carrier mobility of ~174 cm2 V−1 s−1 and an ultralow κ l a t of ~0.42 W m−1 K−1 are realized in this system, leading to an ultrahigh zT of ~2.0 at 723 K. The corresponding single-leg module demonstrates a high conversion efficiency of ~12.6% with a 425 K temperature difference, and the two-pair module of Mg3Sb2/MgAgSb displays ~7.1% conversion efficiency with a 276 K temperature difference. This work paves a pathway to improve the thermoelectric performance of Mg3Sb2-based materials, and represents a significant step forward for the practical application of Mg3Sb2-based devices. The authors modify complex defect microstructure in Mg3Sb2-based thermoelectrics to reduce structural disorder and promote microstructural evolution, synergistically optimizing electron and phonon transport via a delocalization effect for high performance. [ABSTRACT FROM AUTHOR]

Oxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco‐friendly constituting elements. Here, adopting a unique synthesis route via chemical co‐precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics (PFmax=$PF_{\text{max}} =$ 21.5 µW cm−1 K−2 and zTmax=$zT_{\text{max}} =$ 0.5 at 1100 K in Zn0.96Al0.04O${\rm Zn}_{0.96} {\rm Al}_{0.04}{\rm O}$) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi‐dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnO thermoelectrics. [ABSTRACT FROM AUTHOR]

p-Type Fe2VAl-based thermoelectrics have been much less investigated compared to their respective n-type counterparts. Thus, it is crucial to identify novel doping strategies to realize enhanced p-type Fe2VAl Heusler compounds. In the current study, the effect of Mn substitution in Fe2V1−xMnxAl is investigated with respect to temperature-dependent electronic transport as well as temperature- and field-dependent magnetic properties. We find an anomalous and unexpected p-type Seebeck coefficient for nominally n-doped Fe2V1−xMnxAl over an extremely large range of concentrations up to x = 0.6. Using density functional theory (DFT) calculations, this is traced back to distinct modifications of the electronic structure, i.e., localized magnetic defect states (m = 2.43μB) at the valence and conduction band edges, and a concomitant pinning of the Fermi level within the pseudogap. Furthermore, we were able to further optimize the thermoelectric properties by co-doping Al antisites in off-stoichiometric Fe2V0.9Mn0.1Al1+y, yielding sizeable values of the power factor, PF = 2.2 mW K−2 m−1 in Fe2V0.9Mn0.1Al1.1 at 350 K, and figure of merit, ZT ∼ 0.1 for highly off-stoichiometric Fe2V0.9Mn0.1Al1.5 at T = 500 K. Our work underlines the prospect of engineering Fe2VAl-based Heusler compounds via magnetic doping to realize enhanced p-type thermoelectris and encourages studies involving other types of co-substitution for Mn-substituted Fe2V1−xMnxAl. [ABSTRACT FROM AUTHOR]

Higher manganese silicides (denoted as MnSiγ ) are a prominent class of intermetallic compound for thermoelectric applications that crystallizes into a Nowotny Chimney Ladder (NCL) phase and constitutes a higher concentration of silicon with odd stoichiometry, typically represented by an irrational number. In this work, the genesis of Si odd stoichiometry and secondary phase relations in silicon-rich and silicon-deficient MnSix is presented to clarify the significance of labile (i.e., easily alterable) Si-subsystem in inheriting the modulated lattice structure with characteristic anharmonicity. The transport properties show an interrelation to the presence of a secondary phase, which is driven by the odd stoichiometry, where the thermoelectric figure of merit (zT) is found to be optimal for MnSi1.74. The structural characterization of rapidly solidified melt-spun ribbons and spark plasma sintered bulk specimens reveal a characteristic presence of MnSi and Si as secondary phases in Si-deficient (x ≈ 1.5) and Si-excess (x ≈ 2) compositions of nominal MnSix, respectively, that coexists with the major MnSiγ based NCL phase. This study provides the fundamental basis of phase evolution and the relevance of odd stoichiometry in silicon-rich manganese silicides which exhibit fascinating phonon dynamics in optimal MnSi1.74 stoichiometry. [ABSTRACT FROM AUTHOR]

In the realm of optoelectronic applications, the incorporation of a metal interlayer between layers of a topological material holds significant potential. The interlayer introduces benefits such as improved charge transfer efficiency, tunable band alignment, plasmonics effect, and enhanced light‐matter interactions, paving the way for more efficient and versatile optoelectronic devices. This work explores the incorporation of gold between Bi2Se3, resulting in an enhancement in the response time of photoresponse of interlayered systems (Bi2Se3‐Au‐Bi2Se3). The introduction of a gold interlayer between Bi2Se3 significantly influences the overlayer structure, crystallinity, crystallite size, and even phonon behavior. Moreover, the responsivity of the interlayered device at a bias (2 V) is found to have high responsivity with fast response and decay time (τr = 0.1 ms, and τd = 24 ms of interlayered systems) as compared to intrinsic Bi2Se3(τr = 0.6 ms, and τd = 28 ms). This change is attributed to the bandgap alteration of the Bi2Se3/Au interface, which is monitored through transient spectroscopy performed at different electric biases. This study suggests that incorporating a gold interlayer holds potential benefits for various optoelectronic applications. [ABSTRACT FROM AUTHOR]

Heterostructures of two‐dimensional materials realise novel and enhanced physical phenomena, making them attractive research targets. Compared to inorganic materials, coordination nanosheets have virtually infinite combinations, leading to tunability of physical properties and are promising candidates for heterostructure fabrication. Although stacking of coordination materials into vertical heterostructures is widely reported, reports of lateral coordination material heterostructures are few. Here we show the successful fabrication of a seamless lateral heterojunction showing diode behaviour, by sequential and spatially limited immersion of a new metalladithiolene coordination nanosheet, Zn3BHT, into aqueous Cu(II) and Fe(II) solutions. Upon immersion, the Zn centres in insulating Zn3BHT are replaced by Cu or Fe ions, resulting in conductivity. The transmetallation is spatially confined, occurring only within the immersed area. We anticipate that our results will be a starting point towards exploring transmetallation of various two‐dimensional materials to produce lateral heterojunctions, by providing a new and facile synthetic route. [ABSTRACT FROM AUTHOR]